This invention relates to novel antiperspirant compounds comprising basic aluminum halides that have a particular molecular size distribution as well as the processes for their production and their use in antiperspirant composition. Basic aluminum halides, particularly chlorides, and their use as effective antiperspirant compounds are well known. Basic aluminum halides are complex structures made up of mixtures of polymeric and monomeric species of various sizes and molecular structures, depending upon their Al:Halide ratio, together with varying amounts of bound or coordinated water. The basic aluminum compounds are generally represented by the empirical formula:Al2(OH)(6-X)Yx.nH2O wherein Y is Cl, Br or I and 0<x<6 and n is about 0.8 to 4. It should be understood that the above formula is simplified because it is intended to include basic aluminum halides containing coordinated or bound molecules of water as well as basic aluminum halide polymer complexes and mixtures of the above.
Many attempts have been made to improve the antiperspirant efficacy and other properties of basic aluminum compounds, by altering its polymeric structure. The enhanced efficacy salts are typically differentiated from the conventional antiperspirant salts by reference to the various aluminum peaks that can be identified when the salt is analyzed by size exclusion chromatography typically HPLC (high pressure liquid chromatography). A suitable chromatographic technique is capable of resolving the Al in aluminum chlorohydroxide in at least four distinct peaks labeled peaks 2 (which includes peak 1 and peak 2), 3, 4 and 5. The retention time at which these peaks appear, their resolutions and their respective peak areas, are the function of the column (or columns) and mobil phase used. In general, enhanced efficacy salts have been described as having an increased peak 4 content, or an increased peak 4 to peak 3 ratio, compared to conventional (unactivated) salts. In several cases, enhanced efficacy salts have been described as having increased “Band II”. It is important to note that generally, Bands I, II, In and IV of one system correspond respectively to peaks 1 and 2 (Band I), 3, 4 and 5 of the other system.
A review of the prior art shows that the known enhanced efficacy salts (measured at 10% solutions) have an HPLC peak 4 to peak 3 area ratio of 0.5 or higher with at least 70% and preferably at least 80% of the aluminum contained in peaks 3 and 4. Thus, enhanced salt will have peak 4 content of at least 20%, and more likely at least 30%, of the total aluminum contained in all the peaks as measured by peak area. In contrast, conventional non-enhanced antiperspirant salt have peak 4 content of the range of about 10% and peak 4 to peak 3 area ratio from about 0.10 to 0.2 or less.
The following is a brief review of the prior art for the preparation of enhanced efficacy aluminum chlorohydroxide powders. Aluminum chlorohydroxides have been reported to be made of three broad basic groups based on their complexing rate with ferron (2-hydroxy-7iodo-5-quinoline sulphonic acid) and have been referred to as Ala, Alb and Alc. Ala has the fastest complexing rate; the Alb group has an intermediate complexing rate and the Alc group has the slowest complexing rate. It is also known that when aqueous solutions of aluminum chlorohydoxides are subjected to size exclusion chromatography, the three groups exhibit different retention times. The Ala group has the longest retention time, which is indicative that it is made up of the lowest molecular size materials, the Alb group has an intermediate retention time, indicating it comprises complexes of intermediate molecular size and the Alc group has the shortest retention time indicating that it is made up of the highest molecular size complexes.
U.K. Patent Application GB 2,048,229 A of Fitzgerald reported that there is a further group of complexes within the aluminum chlorohydroxides which has not been previously identified and is more efficacious as an antiperspirant than the known groups referred to above. This more efficacious group was referred to as Alc and is usually present in amounts from about 10% to 30% by weight in aluminum chlorohydroxide and that aluminum chlorohydroxides can be modified so as to contain substantially higher amount of the Alc group. The increase in Alc group is achieved by diluting aluminum chlorohydroxide solution with water to achieve concentration of at least 5% by weight, preferably 7.5% and more preferably 10% by weight or more, and aging the solution at a temperature above 50° C. and below 100° C. until the desired conversion is achieved. Good results were obtained at concentration between 10% and 25% (page 2, line 3 of that reference); these parameters are outside those employed in the process of the present invention.
In U.S. Pat. No. 4,359,456 of Gosling, et al., it is disclosed that basic aluminum halides obtained by conventional method can be further broken down from high molecular weight polymers by diluting concentrated solutions thereof to lower aqueous concentrations (aluminum concentration of 10% to 35% by weight) and heating at a temperature of 50° C. to 140° C. for a period of time sufficient to provide a Band III percent aluminum value of at least 20%. The patent is silent concerning the distribution of, and any significance attributable to, aluminum species in Bands other than Band III. Notable also is the fact that process parameters are different from the present invention.
In U.S. Pat. No. 4,775,528 of Callahan, et al., it is reported that enhanced efficacy Al/Zr product is achieved by heating a 2% to 20% by weight aqueous solution of aluminum chlorohydroxide until the ratio of the height of the peak 4 corresponding to kd=0.7, i.e., Band III, to that of peak corresponding to kd=0.5, i.e., Band II, is at least 2:1 and at least 80%, and preferably at least 90%, of the total aluminum is present within the peaks corresponding to peaks 4 and 3 (Bands III and II) (Column 2, lines 60-61). The resulting product contains lower molecular weight polymers to increase efficacy, but also has a wider polydispersity. The antiperspirant composition comprises zirconyl hydroxy chloride solution and an amino acid to provide an atomic ratio of Al:Zr from 6:1 to 1:1. There is no range or specification delineated for aluminum species in peaks 1 and 2 and peak 5. Peak 4 should have at least 53% of aluminum species to meet the requirements (a) of peak 4 to peak 3 area ratio of at least 2:1 and (b) sum of peaks 4 and 3 areas to be 80% of the total aluminum present within all the peaks.
U.S. Pat. No. 4,818,512 of Markarian discloses a process for preparing enhanced efficacy aluminum chlorohydroxide product containing from about 77% to about 85% of an aluminum chlorohydroxide molecular species having a kd value of equal to about 0.4 (Band III species) comprising heating an about 5% aqueous solutions of aluminum chlorohydroxide at a temperature of from about 60° C. to about 132° C. and for a period of from about 30 minutes to about three months to produce a reaction product and spray drying the reaction product.
It also reported the effect of the concentration of aluminum chlorohydroxide (a series of 5/6 basic aluminum chlorohyroxides were prepared ranging in concentration from 5% to 25% by weight) solution, the time of heating and the temperature of heating on the distribution of various molecular species of aluminum. For convenient reference the following results are reproduced from Table 1, Column 6 of U.S. Pat. No. 4,818,512.
TABLE ITEMP.% Peak HeightCONC.(° C.)TIMEpHKd = 0Kd = 0.25Kd = 0.4Kd = 0.6 5% 60*3 M4.58 11877410%603 M4.41 12966415%603 M4.33 34352220%603 M4.25 94839525%604.8 M  4.00413917425%RT04.267118 64(initial)Band IBand IIBand IIIBand IVThese results disclosed by U.S. Pat. No. 4,818,512 clearly demonstrate that at higher concentrations (25% or higher) the percent of lower molecular Band III and Band IV species obtained is very low (less than 20% and 5% respectively) despite aging at an elevated temperature for more than 3 months. Such compositions and process parameters of the '512 patent are clearly outside the range of those contemplated by the present invention.
In U.S. Pat. No. 4,859,446 of Abrutyn is disclosed an improved process for preparing an enhanced antiperspirant which is characterized by size exclusion chromatograph corresponding to Band III of the standard Basic Aluminum Chloride solution and a Band III percent aluminum value of at least 40% which comprises reacting an aluminum compound of the formula: AlnXm, wherein X is Cl, Br, F, I, SO4 and NO2, n is 1 or 2 and m is 1 or 3, with aluminum metal in an aqueous medium at a temperature between 50° C. and 195° C. until a ratio of aluminum to anion of 0.50-2.5:1 is obtained and recovering the resultant product without elevated temperature aging. Here also the product composition is different from the product of this invention as characterized by HPLC and the process is different.
In U.S. Pat. No. 4,871,525 of Giovanniello is disclosed a process which comprises heating in water at a temperature from about 50° C. to about 100° C. aluminum metal preferably in the form of pellets or powder, with a halogen containing compound selected from HXn, where X is chlorine, bromine or iodine. The amount of water used is such as to have concentration of the polymer in percent by weight in the range from about 8% to about 35% preferably from about 15% to about 25% and more preferably from about 17% to about 22% by weight. The reaction temperatures are preferably in the range from about 95° C. to about 100° C. and should not be high enough to create reflux conditions. 100% of the aluminum containing polymers are found in Bands II, III and IV and Band III contains at least 20% of the total aluminum polymers. Narrow polydispersity is claimed when the batch concentration falls within 17-22% and metal to chloride atomic ratio does not exceed 2.00:1. The product of the '525 patent differs from the U.S. Pat. No. 4,359,456 and U.S. Pat. No. 4,775,528 patents in that '525 patent claims zero aluminum species in Band I. However, none of the three patents disclose, teach or suggest compositions containing specific aluminum species concentration in peak 5 or Band IV.
U.S. Pat. No. 4,900,534 of Inward discloses a process for the direct preparation of aluminum zirconium halohydrates of enhanced efficacy having size-exclusion chromatograph of which the Band III proportion is at least 20%. However, the process parameters and product characterization disclosed in that patent differ significantly from those of the present invention.
U.S. Pat. No. 4,944,933 of Inward discloses a process for the manufacture of basic aluminum chloride solutions with 7.5% to 13% by weight, having an aluminum chloride molar ratio in the range of 1.7 to 2.2:1 and which has Band III fraction of at least 20% and drying the final basic aluminum chloride solution to give hydrated powder having Band III fraction of at least 20%. This patent also does not teach the significance of the concentration of aluminum species in Bands II and IV and Al:Cl molar ratio is outside the range of the current invention.
U.S. Pat. Nos. 5,358,694 and 5,356,609 of Giovanniello disclose a process which comprises reacting aluminum metal with hydrohalogen acid having the formula HX wherein X is Cl, Br and I or with aluminum halide hexahydrate AlX3.6H2O wherein X is Cl, Br or I, at a temperature of about 50° C. to about 100° C. the concentration of the product being 8% to about 25% by weight of the solution. The basic aluminum compound wherein the Al/halide ratio is about 1:1 to 2.1:1 is recovered from the hot solution by spray drying. 100% of the polymers are found in Bands II, III and IV with no part of the product found in Band I. Band III of the product contains at least 25% of the polymer. Aluminum metal may contain reaction catalyst comprising metal wherein the metal is copper utilized at about 0.005 to about 0.3 weight percent or iron utilized at about 0.02 to about 0.25 weight percent based on the weight of aluminum. Aluminum species concentration range in Bands II and IV is not defined.
U.S. Pat. Nos. 5,595,729, 5,626,827 of Barr, et al., disclose antiperspirant active compositions comprising basic aluminum material having the empirical formula Al2(OH)6-aXa where 0.5≦a≦5 and X is a univalent complex oxo anion of nitrogen or a univalent complex oxo anion of a halogen (for example, NO3, ClO3, ClO4 and IO4) being further characterized by chromatography peaks corresponding to peak 3 and peak 4 of the size exclusion HPLC chromatogram with a peak 4 (Band III) relative area of at least 25% and peak 3 (Band II) relative area of less than 60%, the sum of the relative peak 3 and peak 4 (Band II and Band III) area being at least 50% and peak 1 less than 10% (chromatographic peaks eluting at shorter retention times than peak 3 corresponding to peaks 1 and 2). The product of that patent is particularly directed to basic aluminum antiperspirant materials containing a univalent complex oxo anion of nitrogen or halogen and not to halogen anion alone and does not require any specific concentration of aluminum species in peak 5 or Band IV.
U.S. Pat. No. 6,149,897 of Swaile discloses a process for making anhydrous compositions containing solubalized enhanced aluminum zirconium antiperspirant wherein the weight ratio of the anhydrous solvent to the zirconium containing and aluminum containing antiperspirant active is from about 1:2 to 20:1 and peak 3 to peak 4 (Band II to Band III) area ratio is at least 0.1:1. The atomic ratio of zirconium to aluminum is from 1:1 to about 4:1. The patent contains no disclosure concerning the concentration of polymeric aluminum species as expressed by the areas of Band I and Band IV. The requisite process parameters and composition of the present invention are outside those employed in the patent.
U.S. Pat. No. 6,451,296 B1 of Li, et al., discloses stable aluminum zirconium antiperspirant compositions in polyhydric alcohol solution with enhanced efficacy having 20-45% by weight concentration on an anhydrous basis and wherein the aluminum to zirconium atomic ratio is from 10:1 to 1:10. The amino acid to zirconium molecular ratio is 0.1 to 2:1 and aluminum and zirconium to anion ratio is from 0.9:1 to 2.1:1. The product is further characterized by Band I relative area value of from 0% to 5% and Band III and IV relative area values of at least 75%.
The patent teaches preparation of stable enhanced efficacy Al/Zr solution by employing polyhydric alcohol as one of the reactants and anti-gelling agent for zirconium. The presence of zirconyl oxychloride promotes depolymerization of aluminum species and yields higher concentration of lower molecular weight species resulting in higher concentration of peak 4. The presence of polyhydric alcohol as an anti-gelling agent minimizes polymerization of zirconium species. However, the high concentration of polyhydric alcohol is not desirable for most antiperspirant formulations due to its tackiness. The novel product of this invention is prepared in the absence of polyhydric alcohol and/or zirconyl chloride.
The process parameters used for the activation of basic aluminum chloride by an indirect process (i.e., heating and or aging a diluted solution) or by direct process where aluminum metal in powder or pellet or other forms is reacted with HX or AlX3.6H2O, wherein X is Cl, Br or I, are clearly outside those employed by the process of the present invention and no prior art has defined composition of basic aluminum halides in terms of concentration of aluminum species in all the four bands to achieve superior efficacy while minimizing the irritancy potential, acid odor associated with low metals to chloride (0.9:1 to 1:1) and making it economically.
The prior art emphasizes and attributes higher efficacy primarily to the increase in concentration of Band III or peak 4 species. The Parekh, et al., U.S. Pat. No. 5,718,876 demonstrates that Band II percent aluminum value of at least 50% and Band III percent value of less than 20% also give enhanced efficacy antiperspirant products. The Carrillo, et al., U.S. Pat. No. 6,436,381 correlated improved efficacy of low metal to chloride ratio (0.9:1 to 1:1) products with peak 5 (or Band IV). Carrillo et al., pointed out that basic aluminum chloride with significant amount of peak 5 (Band IV) is not known to have any efficacy advantage and is not typically used in commercial products thus that disclosure teaches away from the basic aluminum halide with significant amount of peak 5. The invention of U.S. Pat. No. 6,436,381 does not embrace the aluminum antiperspirant salts and is directed only to aluminum-zirconium salts having a substantial peak 5. No other prior art known has demonstrated that significant improvement in efficacy can be obtained by controlling concentration of species present in Bands I, II, III and IV while maintaining Al:Cl ratio in the range of 1.2:1 to 1.5:1 and preferably 1.3:1 to 1.4:1 and at high anhydrous solids (30-40%) concentrations. This is achieved by careful control of the metals to chloride ratio, maintenance of proper solids concentration and with or without aging at room temperature.
Basic aluminum chlorides having a preponderance of Band III aluminum species and process for the production of such compounds have a number of disadvantages; for example, these processes generally require either dilution of conventional aluminum chlorohydroxide to 5-20% weight concentration or thermal treatment of dilute solutions at high temperatures to effect the polymer conversion and then rapid drying of the solution into a powder form as the solution itself is not stable. Alternately, the solution can be prepared directly by reacting aluminum powder or pellets with HX or AlX3.6H2O in an aqueous phase at a lower weight percent concentration, for example, 15-20%. In any case, the cost of drying the dilute solution to powders is significantly higher. All of the cited prior art, except one, attributes higher efficacy to increase concentration of Band III (peak 4) aluminum species; the concentration ranging from at least 20% to as high as 85%.
U.S. Pat. Nos. 5,718,876 and 6,024,945 of Parekh, et al., disclose preparation of enhanced efficacy basic aluminum halides solutions having solids concentration of about 28% to about 42% on an anhydrous basis having Al:anion ratio of about 1.2 to 1.8 and having Band II percent aluminum value of at least about 50% and Band III percent aluminum values of less than 20% and Band I percent aluminum value of less than about 1%. The basic aluminum chlorides of the process disclosed herein overcame the disadvantages of the prior art and demonstrated excellent antiperspirancy. The disclosure of U.S. Pat. Nos. 5,718,876 and 6,024,945 are incorporated herein by reference.
It is important to note that the weight percentage of antiperspirant salt is indicated herein as percent of anhydrous solid (% A.S.), which excludes any bound water. This is calculated in accordance with the following equation:% A.S.=% Al[26.98x+17.01 (3x−1)+35.453]/26.98x wherein x=Al/Cl ratio.
The following comparison illustrates the difference in the calculation of antiperspirant salt between the present method and the previous standard industry method.
TABLE IISaltStandard MethodPresent Method5/6 Basic aluminum chlorohydrate50% w/w40.8%solutionThus, 28% anhydrous solids refers to 34.3% weight percent solution using the standard method.
In the above mentioned U.S. Pat. No. 5,718,876 basic aluminum halides and nitrates are prepared by reacting an aluminum powder, an aluminum halide or nitrate solution and water at a temperature greater than about 85° C. The reaction is maintained until reaction products having an Al:anion ratio of about 1.2 to about 1.8 and a solution solids concentration of about 28 to about 42 weight percent on an anhydrous basis are obtained. The reaction product is characterized as having a Size Exclusion Chromatography Test Band having a Band II percent aluminum value of at least about 50% and Band III percent aluminum value of less than 20%. Those products preferably also have a Band I percent aluminum value of less than about 1%. The method of that patent also encompasses the preparation of basic aluminum halide, nitrate and zirconium complexes. The zirconium compounds are preferably buffered with amino acid. The method of that patent for preparing these compounds comprises reacting, at room temperature, a basic aluminum halide and nitrate solution, with a zirconium compound or a zirconium/amino acid complex. The products obtained have a preponderance of aluminum species in Band II and the basic aluminum halide and zirconium complexes of these compounds provide improved efficacy when made into an antiperspirant composition using any of the usual vehicles of formulations known in the art.